The second variation is adding a temperature \(\tau \)  to the softmax [1]}:
\(l_{\mathrm {contrastive}}\left(f(\mu _{ti}^{\prime }), \mu \right) = - \log \frac{\exp (f(\mu _{ti}^{\prime }) \cdot \mu _{ti}) / \tau }{\sum _{s, j} \exp \left( f(\mu _{ti}^{\prime }) \cdot \mu _{sj} / \tau \right) }.\) 
